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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
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4 -- --
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5 -- S Y S T E M . V E C T O R S . B O O L E A N _ O P E R A T I O N S --
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6 -- --
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7 -- B o d y --
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8 -- --
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145
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9 -- Copyright (C) 2002-2019, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 package body System.Vectors.Boolean_Operations is
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33
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34 SU : constant := Storage_Unit;
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35 -- Convenient short hand, used throughout
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36
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37 -- The coding of this unit depends on the fact that the Component_Size
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38 -- of a normally declared array of Boolean is equal to Storage_Unit. We
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39 -- can't use the Component_Size directly since it is non-static. The
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40 -- following declaration checks that this declaration is correct
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41
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42 type Boolean_Array is array (Integer range <>) of Boolean;
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43 pragma Compile_Time_Error
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44 (Boolean_Array'Component_Size /= SU, "run time compile failure");
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45
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46 -- NOTE: The boolean literals must be qualified here to avoid visibility
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47 -- anomalies when this package is compiled through Rtsfind, in a context
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48 -- that includes a user-defined type derived from boolean.
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49
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50 True_Val : constant Vector := Standard.True'Enum_Rep
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51 + Standard.True'Enum_Rep * 2**SU
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52 + Standard.True'Enum_Rep * 2**(SU * 2)
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53 + Standard.True'Enum_Rep * 2**(SU * 3)
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54 + Standard.True'Enum_Rep * 2**(SU * 4)
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55 + Standard.True'Enum_Rep * 2**(SU * 5)
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56 + Standard.True'Enum_Rep * 2**(SU * 6)
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57 + Standard.True'Enum_Rep * 2**(SU * 7);
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58 -- This constant represents the bits to be flipped to perform a logical
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59 -- "not" on a vector of booleans, independent of the actual
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60 -- representation of True.
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61
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62 -- The representations of (False, True) are assumed to be zero/one and
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63 -- the maximum number of unpacked booleans per Vector is assumed to be 8.
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64
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65 pragma Assert (Standard.False'Enum_Rep = 0);
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66 pragma Assert (Standard.True'Enum_Rep = 1);
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67 pragma Assert (Vector'Size / Storage_Unit <= 8);
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68
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69 -- The reason we need to do these gymnastics is that no call to
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70 -- Unchecked_Conversion can be made at the library level since this
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71 -- unit is pure. Also a conversion from the array type to the Vector type
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72 -- inside the body of "not" is inefficient because of alignment issues.
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73
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74 -----------
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75 -- "not" --
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76 -----------
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77
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78 function "not" (Item : Vectors.Vector) return Vectors.Vector is
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79 begin
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80 return Item xor True_Val;
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81 end "not";
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82
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83 ----------
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84 -- Nand --
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85 ----------
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86
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87 function Nand (Left, Right : Boolean) return Boolean is
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88 begin
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89 return not (Left and Right);
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90 end Nand;
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91
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92 function Nand (Left, Right : Vectors.Vector) return Vectors.Vector is
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93 begin
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94 return not (Left and Right);
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95 end Nand;
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96
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97 ---------
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98 -- Nor --
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99 ---------
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100
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101 function Nor (Left, Right : Boolean) return Boolean is
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102 begin
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103 return not (Left or Right);
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104 end Nor;
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105
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106 function Nor (Left, Right : Vectors.Vector) return Vectors.Vector is
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107 begin
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108 return not (Left or Right);
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109 end Nor;
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110
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111 ----------
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112 -- Nxor --
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113 ----------
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114
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115 function Nxor (Left, Right : Boolean) return Boolean is
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116 begin
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117 return not (Left xor Right);
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118 end Nxor;
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119
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120 function Nxor (Left, Right : Vectors.Vector) return Vectors.Vector is
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121 begin
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122 return not (Left xor Right);
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123 end Nxor;
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124
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125 end System.Vectors.Boolean_Operations;
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